I was just going to add that producers are responsible for the animals they raise. Most of the commodities have on-farm handling procedures on how to move animals from one pen to another, or moving from their farm onto a truck. That's where training comes into play. Bearing in mind that loading animals is stressful, taking them off the truck is stressful. They have to be certain that even before they get to that point, that animal can make the trip. There are situations where things are unseen, whether there's a heart condition within the animal or whatnot that develops during transportation.
There are steps in place to address some of the issues beforehand, but it's the small percentage of things that may happen, whether it's in a barn or on a truck.